A practical approach to transforming extended ER diagrams into the relational model

Abstract

Constructs for the extended ER model are defined and classified as a basis for transformation into the relational model. Transformation rules are developed for the different possible forms of n-ary relationships among entities including relationship connectivity, membership class, existence dependency, and generalization and subset hierarchies. Although normalization is not necessarily preserved under the transformation rules, it is feasible to implement a sequence of transformation and normalization operations without loss of information. This approach provides a practical solution to the modeling of real-world problems using first the extended ER model and then its refinement into the relational model.